/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.solr.search.function;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Searcher;

import java.io.IOException;
import java.util.Map;

public abstract class DualFloatFunction extends ValueSource {
	protected final ValueSource a;
	protected final ValueSource b;

	/**
	 * @param a
	 *            the base.
	 * @param b
	 *            the exponent.
	 */
	public DualFloatFunction(ValueSource a, ValueSource b) {
		this.a = a;
		this.b = b;
	}

	protected abstract String name();

	protected abstract float func(int doc, DocValues aVals, DocValues bVals);

	@Override
	public String description() {
		return name() + "(" + a.description() + "," + b.description() + ")";
	}

	@Override
	public DocValues getValues(Map context, IndexReader reader)
			throws IOException {
		final DocValues aVals = a.getValues(context, reader);
		final DocValues bVals = b.getValues(context, reader);
		return new DocValues() {
			@Override
			public float floatVal(int doc) {
				return func(doc, aVals, bVals);
			}

			@Override
			public int intVal(int doc) {
				return (int) floatVal(doc);
			}

			@Override
			public long longVal(int doc) {
				return (long) floatVal(doc);
			}

			@Override
			public double doubleVal(int doc) {
				return floatVal(doc);
			}

			@Override
			public String strVal(int doc) {
				return Float.toString(floatVal(doc));
			}

			@Override
			public String toString(int doc) {
				return name() + '(' + aVals.toString(doc) + ','
						+ bVals.toString(doc) + ')';
			}
		};
	}

	@Override
	public void createWeight(Map context, Searcher searcher) throws IOException {
		a.createWeight(context, searcher);
		b.createWeight(context, searcher);
	}

	@Override
	public int hashCode() {
		int h = a.hashCode();
		h ^= (h << 13) | (h >>> 20);
		h += b.hashCode();
		h ^= (h << 23) | (h >>> 10);
		h += name().hashCode();
		return h;
	}

	@Override
	public boolean equals(Object o) {
		if (this.getClass() != o.getClass())
			return false;
		DualFloatFunction other = (DualFloatFunction) o;
		return this.a.equals(other.a) && this.b.equals(other.b);
	}
}
